Clock control is handed over in a bus circuit from a first circuit (14) to a second circuit (12). A clock conductor (10a) is driven to a predetermined voltage level with the driver circuit of the first circuit after a last clock period following the start of execution of the handover command and to continue driving the clock conductor (10a) to the predetermined voltage level for a first time-interval. The clock conductor (10a) is driven to the predetermined voltage level with the driver circuit of the second circuit after a second time interval following the start of execution of the handover command until a third time interval has elapsed following the end of the second time interval. Subsequently the clock conductor (10a) is driven under control of the clock circuit (140) of the second circuit (14). The first time interval contains a first integer number P1 of periods of a first clock signal of the first circuit and the second and third time interval contain a second and third integer number P2, P3 of periods of a second clock signal of the second circuit, a duration corresponding to the second integer number P2 equaling at least a pulse duration of the first clock signal, a duration corresponding to the first integer number P1 equaling at least a duration corresponding to the second integer number P2 plus one, a duration corresponding to the second plus third integer P2, P3 equaling at least a duration corresponding to the first number P1 plus one.
Legal claims defining the scope of protection, as filed with the USPTO.
1. An apparatus comprising: a communication bus that comprises a clock conductor; a plurality of circuits coupled to the bus, each of the plurality of circuits comprising a clock circuit and a driver circuit with an input coupled to the clock circuit and an output coupled to the clock conductor; and at least one control circuit arranged to be responsive to a hand-over command from the communication bus for handing over clock control from a first of the plurality of circuits to a second of the plurality of circuits, the at least one control circuit arranged to cause the driver circuit of the first circuit to drive the clock conductor to a predetermined voltage level after a last clock period following the start of execution of the hand-over command and to continue driving the clock conductor to the predetermined voltage level for a first time-interval.
2. The apparatus of claim 1 , wherein the at least one control circuit is configured to cause the driver of the second circuit to start driving the clock conductor to the predetermined voltage level after a second time interval following the start of execution of the hand-over command until a third time interval has elapsed following the end of the second time interval, and subsequently drive the clock conductor under control of a clock circuit of the second circuit.
3. The apparatus of claim 1 , wherein the at least one control circuit is configured to start execution of the hand-over command in response to detection of a sync data pattern.
4. The apparatus of claim 1 , wherein the first circuit comprises a clock frequency different than the second circuit, further comprising a bus manager configured to measure the clock frequencies.
5. The apparatus of claim 4 , wherein the bus manager configured to determine a ratio between the frequencies of the first and second circuits and select a plurality of factors for use in equalizing the frequencies.
6. The apparatus of claim 4 , wherein the bus manager comprises a table of predetermined factors for use in equalizing the frequencies.
7. The apparatus of claim 1 , wherein the at least one control circuit is configured to cause the first circuit to enter a sleep mode after completion of the hand-over.
8. A portable device comprising: a digital loudspeaker device; a communication bus coupled to the digital loudspeaker device, the communication bus comprising a clock conductor a plurality of circuits coupled the digital loudspeaker device through the communication bus, each of the plurality of circuits comprising a clock circuit and a driver circuit with an input coupled to the clock circuit and an output coupled to the clock conductor; and at least one control circuit arranged to be responsive to a hand-over command from the communication bus for handing over clock control from a first of the plurality of circuits to a second of the plurality of circuits, the at least one control circuit arranged to cause the driver circuit of the first circuit to drive the clock conductor to a predetermined voltage level after a last clock period following the start of execution of the hand-over command and to continue driving the clock conductor to the predetermined voltage level for a first time-interval.
9. The portable device of claim 8 , wherein the at least one control circuit is configured to cause the driver of the second circuit to start driving the clock conductor to the predetermined voltage level after a second time interval following the start of execution of the hand-over command until a third time interval has elapsed following the end of the second time interval, and subsequently drive the clock conductor under control of a clock circuit of the second circuit.
10. The portable device of claim 8 , wherein the at least one control circuit is configured to start execution of the hand-over command in response to detection of a sync data pattern.
11. The portable device of claim 8 , wherein the first circuit comprises a clock frequency different than the second circuit, further comprising a bus manager configured to measure the clock frequencies.
12. The portable device of claim 11 , wherein the bus manager configured to determine a ratio between the frequencies of the first and second circuits and select a plurality of factors for use in equalizing the frequencies.
13. The portable device of claim 11 , wherein the bus manager comprises a table of predetermined factors for use in equalizing the frequencies.
14. The portable device of claim 8 , wherein the at least one control circuit is configured to cause the first circuit to enter a sleep mode after completion of the hand-over.
15. A method of operating an apparatus that comprises a communication bus that comprises a clock conductor, the method comprising: handing over clock control from a first circuit to a second circuit; driving the clock conductor to a predetermined voltage level with a driver circuit of the first circuit after a last clock period following a start of execution of a hand-over command and continue driving the clock conductor to the predetermined voltage level for a first time-interval; and subsequently driving the clock conductor under control of the clock circuit of the second circuit.
16. The method of claim 15 , further comprising driving the clock conductor to the predetermined voltage level, with a driver of the second circuit, after a second time interval following the start of execution of the hand-over command until a third time interval has elapsed following the end of the second time interval, and subsequently driving the clock conductor under control of a clock circuit of the second circuit.
17. The method of claim 15 , wherein driving the clock conductor further comprising starting the execution of the hand-over command in response to detection of a sync data pattern.
18. The method of claim 15 , wherein the first circuit comprises a clock frequency different than the second circuit, further comprising: measuring the clock frequencies of the first and second circuits.
19. The method of claim 18 , further comprising: determining a ratio between the frequencies of the first and second circuits; and selecting at least one factor for use in equalizing the frequencies.
20. The method of claim 19 , further comprising: placing the first circuit to enter a sleep mode after completion of the hand-over.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
March 22, 2010
January 18, 2011
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